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20120928
20121006
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is in decline. researchers at the australian institute of marine science say the reef has lost half of its coral cover over the past 27 years. there are multiple causes, including a destructive kind of starfish shown here. we look at what's behind it and what's at stake-- in australia and around the world-- with nancy knowlton, a coral reef biologist and a chair of marine science at the smithsonian national museum of natural history here in washington. welcome. >> thanks. how has all of this coral died off? do we know what's causing it? is it all that... >> it's not all the star fish. the star fish is about 42%. typhoons, big strong storms another 48% and then coral bleaching is the remaining 10% which is caused whenever the water gets too hot. >> ifill: so this is human causedded? >> yes. most of it is human caused. i mean a coral reef naturally goes through cycles of up and down. but it shouldn't be declining by half over course of 27 years. >> ifill: i feel like we have talked before about the declining coral cover. but not... but i'm wondering whether it's now picking up speed or whether thi
. there is some corals that live for many thousands of yeernz we found through some of the science we do we can drill holes down to the center of the corals and look at annual growth rings and we can look at when, in fact, when the first agriculture in australia happened, we saw a change in the type of chemistry that the annual growth rings and coral were depositing. so we have seen a chronology of increased siltation, of increased fertilization, of
Search Results 0 to 8 of about 9 (some duplicates have been removed)